Program chuong trinh nhap so

uses crt;
Var i,n,S: integer;
Begin
Clrscr;
Write ('Nhap so can kiem tra n: ');

readln(n);

if n mod 2=0 then writeln (n,' la so chan);

if n mod 2<>0 then writeln (n,' la so le);

If (n=0) or (n=1) then
Writeln(n,' Khong phai la so nguyen to')
Else
Begin
i:=1;
Repeat
i:= i+1;
Until (n mod i= 0) or (i*i>n);
If i*i>n then
Writeln (n,' la so nguyen to')
Else
Writeln (n,' khong phai la so nguyen to');
End;

for i:=1 to n do

if n mod i=0 then s:=s+i;

if s=n then writeln (n,' la so hoan hao')

else writeln (n,' khong phai la so hoan hao');
Readln;
End.

Chương trình khá dài nhưng bù lại chương trình sẽ chạy nhanh hơn.

program kiemtraso;

uses crt;

var n,i,s:integer;

       kt:boolean;

begin

clrscr;

repeat

     write('Nhap n: ');   readln(n);

     if (n<1000) or (n>9999) then write('N phai co 4 chu so');

until (n>=1000) and (n<=9999);

if n mod 2=0 then writeln(n,' la so chan')

     else writeln(n,' la so le');

kt:=true;

for i:=2 to trunc(sqrt(n)) do

  if n mod i=0 then 

      begin

          kt:=false;

          break;

      end;

if kt=true then writeln(n,' la so nguyen to')

    else writeln(n,' khong phai so nguyen to');

s:=0;

for i:=1 to n div 2 do

  if n mod i=0 then s:=s+i;

if s=n then writeln(n,' la so hoan hao')

   else writeln(n,' khong la so hoan hao');

readln

end.

Cho mình ctlhn nha.